{"paper":{"title":"Optical counterparts of two ULXs in NGC5474 and NGC3627 (M66)","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"A.Akyuz, A.Valeev, A.Vinokurov, H.Avdan, K.Atapin, N.Aksaker, O.Sholukhova, S.Avdan, S.Fabrika","submitted_at":"2015-10-27T14:15:26Z","abstract_excerpt":"We identified two optical counterparts of brightest ultraluminous X-ray Sources (ULXs) in galaxies NGC5474 and NGC3627 (M66). The counterparts in Hubble Space Telescope images are very faint, their V magnitudes are 24.7 ($M_V \\approx -4.5$) and 25.9 ($M_V \\approx -4.2$), respectively. NGC5474 X-1 changes the X-ray flux more than two orders of magnitude, in its bright state it has $L_X \\approx 1.6 \\times 10^{40}$ erg/s, the spectrum is best fitted by an absorbed power-law model with a photon index $\\Gamma \\approx 0.94$. M66 X-1 varies in X-rays with a factor of ~2.5, its maximal luminosity bein"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1510.07915","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}